Effects of Nb doping on highly fatigue-resistant thin films of (Pb0.8Ba0.2)ZrO3 for ferroelectric memory application

Hung, Cheng-Lung; Wu, Tai–Bor

doi:10.1016/j.jcrysgro.2004.10.013

Cited by 8 publications

(3 citation statements)

References 17 publications

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“…), film thickness, and testing conditions. [155][156][157][158] It is because of the numerous influencing factors that there are many ways to improve the ferroelectricity of perovskite ferroelectric oxide films. Recently, Cho et al [159] added 25% BiFeO 3 (BFO) to SrTiO 3 (STO) and BaTiO 3 (BTO), respectively, to form BFO25-BTO75 and BFO25-STO75 solid solution films, and compared with undoped BTO100 film.…”

Section: Improved Ferroelectric Properties By Alloyingmentioning

confidence: 99%

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Perovskite Oxide Ferroelectric Thin Films

Tian

Yang

2022

Adv Elect Materials

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be roughly divided into perovskite-type, lithium niobate type, tungsten bronze type, potassium dihydrogen phosphate type, triglycine sulphate type, Rochelle salt, ferroelectric liquid crystal, and ferroelectric polymer. Among these ferroelectric thin film materials, perovskite ferroelectric films and ferroelectric polymer films are relatively well-studied films. The outstanding ductility and flexibility of ferroelectric polymer films like polyvinylidene fluoride (PVDF) have made them popular in flexible electrical devices. [7][8][9] However, some disadvantages of ferroelectric polymer films, such as low polarization strength, large coercive field, slow switching speed, and poor temperature resistance limit their application in fields including ferroelectric memory, piezoelectric energy harvesting or sensors. [10][11][12] To apply them to these fields, they need to be appropriately combined with perovskite oxide materials to improve their ferroelectric properties. For example, some researchers doped 0.5((Ba 0.7 Ca 0.3 )TiO 3 )-0.5(Ba(Zr 0.2 Ti 0.8 ) O 3 ) (BCZT) ceramic particles into PVDF to make BCZT/PVDF composite film. PVDF is a semicrystalline ferroelectric polymer, doping it with BCZT improves its crystallinity and hence its dielectric constant. The dielectric constants of the γ-PVDF phase and α-PVDF phase in pure PVDF films are ≈10 and 7.5. After doping with BCZT, the dielectric constants increase to 31 and 20, which improves the ferroelectric properties of PVDF. [13] There are many other examples of enhancing the ferroelectric properties of PVDF films by doping with perovskite oxides. [14][15][16][17][18][19][20] Obviously, enhancing the ferroelectric properties of PVDF by this method will make the preparation process relatively tedious and is not conducive to mass production. It is not as convenient as growing perovskite ferroelectric films directly on flexible substrates. In addition, polymers' poor temperature resistance limits their utilization compared to ferroelectric oxide thin film materials' superior temperature resistance and physical properties. The composite dielectric film composed of BiFeO 3 (BFO) and SrTiO 3 (STO) has a reversible energy storage density (U e ) of about 70 J cm −3 at room temperature and can operate stably between −60 and 100 °C. [21] BaZr 0.35 Ti 0.65 O 3 (BZT) has a U e of 78.7 J cm −3 at room temperature and can work stably between −150 and 200 °C, and the U e still exceeds 40 J cm −3 at 200 °C. [22] But polymer-based ferroelectric materials often cannot be applied at high temperatures and have a low energy storage density (<40 J cm −3 ). [23,24] The high temperature special design can meet the temperature requirements, but the dielectric properties need more optimization. [25,26] The spontaneous polarization of BaTiO 3 (BTO) is about 25 µC cm −2 , [27] and the spontaneous polarization of stress-modulated BTO Perovskite oxide thin film materials are used in various fields of human life due to their excellent physical properties. The high performance thin films in turn prov...

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Section: Improved Ferroelectric Properties By Alloyingmentioning

confidence: 99%

“…), film thickness, and testing conditions. [ 155–158 ] It is because of the numerous influencing factors that there are many ways to improve the ferroelectricity of perovskite ferroelectric oxide films. Recently, Cho et al.…”

Section: Fundamental Physical Properties and Applications Of Perovski...mentioning

confidence: 99%

Perovskite Oxide Ferroelectric Thin Films

Tian

Yang

2022

Adv Elect Materials

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“…9 For the ferroelectric material, the simple perovskite structure material ͑Pb 1−x Ba x ͒ZrO 3 ͑PBZ͒ 10,11 with x = 0.2−0.4 has received more and more attention recently because the ferroelectric PBZ thin film has high fatigue resistance. 12,13 This is because of the exclusion of Ti ions so that the PBZ film contains less oxygen vacancies than PZT and exhibits excellent fatigue resistance. In addition, the large coercive electric field characteristic of PBZ is advantageous to obtain large memory windows in FET-type FeRAMs.…”

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Lead Barium Zirconate Ferroelectric Films with ZrO[sub 2] Buffer Layer for Nonvolatile Memory Applications

Chen

Lin

et al. 2006

Electrochem. Solid-State Lett.

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Ferroelectric ͑Pb 1−x Ba x ͒ZrO 3 ͑PBZ͒ thin films with different Pb/Ba ratio ͑Pb/Ba = 75/25, 70/30, 65/35͒ were fabricated by a sol-gel process. Electrical properties of PBZ films on Pt/Ti/SiO 2 /Si substrates ͑metal/ferroelectric/metal structure͒ and on ZrO 2 /Si substrates metal/ferroelectric/insulator/semiconductor ͑MFIS͒ structure were investigated. The dielectric and ferroelectric properties depend greatly on the Pb/Ba ratio of the PBZ films. For the MFIS structure, the Pb/Ba = 70/30 film shows the best memory property with memory window of 0.9 V when it was scanned at ±5 V. Experimental results demonstrate that ferroelectric PBZ films with ZrO 2 -buffered MFIS structure is suitable for non-volatile field effect transistor-type ferroelectric random access memory applications.Recently, metal/ferroelectric/insulator/semiconductor ͑MFIS͒ structures have attracted much attention in field-effect transistor ͑FET͒-type ferroelectric random access memory ͑FeRAM͒ applications. [1][2][3][4][5] In comparison with current commercial capacitortype FeRAMs, the FET-type FeRAM has more advantages, including small cell size, simple process ͑much lower cost͒, and nondestructive read-out ͑NDRO͒ operation feature. The original concept of the FET-type FeRAM with a metal-ferroelectric-semiconductor ͑MFS͒ structure was proposed by Bell Laboratory in 1957. 6 However, no commercially available devices have been fabricated. This is due to the problems of short retention time caused by the poor ferroelectric/semiconductor interface and the interdiffusion between layers. In order to solve this problem, an insulating layer ͑high dielectric constant, k, material͒ which acts as a diffusion barrier is inserted into the ferroelectrics and the semiconductor to form the MFIS structure. Insulating buffer layers such as CeO 2 , ZrO 2 , and Y 2 O 3 have relatively high dielectric constant of 10-25, low leakage current, and good interface characteristic with Si. 7,8 Among them, ZrO 2 is one of the promising candidate materials as buffer layers for the MFIS structure due to its high thermal stability in direct contact with Si. 9 For the ferroelectric material, the simple perovskite structure material ͑Pb 1−x Ba x ͒ZrO 3 ͑PBZ͒ 10,11 with x = 0.2−0.4 has received more and more attention recently because the ferroelectric PBZ thin film has high fatigue resistance. 12,13 This is because of the exclusion of Ti ions so that the PBZ film contains less oxygen vacancies than PZT and exhibits excellent fatigue resistance. In addition, the large coercive electric field characteristic of PBZ is advantageous to obtain large memory windows in FET-type FeRAMs.In this study, the MFIS capacitor structure was fabricated using PBZ as ferroelectric material and ZrO 2 as the insulating buffer layer material. Besides, the metal/ferroelectric/metal ͑MFM͒ capacitor was also fabricated. To find the optimal composition of the PBZ film which is best for the FET-type FeRAM application, the effect of Pb/Ba ratio on properties of PBZ films was investigated using the MFM struc...

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